Tridimensional radio direction indicator



Feb. 18, 1941. i J. LYMAN 2,231,929

TRIDIIENSIONAL RADIO DIRECTION INDICATOR Filed April 29, 1937 2Sheets-Sheet 2 U.H.F' 96f TRANS.

INV TOR @5e/:R L lMAN Mm N the provision of a novel Parenteel-'ea 1s,1941 UNITED l STATE 'ramnmxsroNAL-aanro nmnc'rron nmrcs'ron.

Joseph Lyman, Huntington. N. YY., assignorfto I Sperry GyroscopeCompany, Inc.I Brooklyn.

N. I., a corporation ot New York Application April 29, 1937. Serial No.139,640

9Claims.

This invention relates, generally, to the three dimensional location o!objects by radio means, and the invention has reference, moreparticulariy, to a novel, tridimensional radio direction indicatoradapted for various uses. Thus, the

(Cl. Z50-11) the sum oi the voltages from both antennae is a maximum,the cathode ray serving to produce a spot onv the screen of the tube incorrespondence with the position of the object in space, the said tubealso serving to simultaneously innovel indicator is adapted for use onaircrag/ dicate any other objects present by additional either forindicating the direction oi appro oi other aircraft, to thereby preventcoil on under conditions of poor or zero visibility/for for use on theground as when locating aircraft for purposes of guniire control, or forcontrolling aircraft landings trom the ground, and for other urposes.

In the above recited uses of the novel device of this invention, it isnecessary that the same indicate the bearing of the desired object, suchas an approaching airplane, both in azimuth and elevation. The merewarning of the presenceoi.' another aircraft in the vicinity isinsuilicient i11-l iormation lor the prevention oi collision betweenapproaching aircraft, since there would be no indication as to thechange of course necessary to avoid collision.

The principal object oi the present invention is to provide a noveltridimensional radio direction indicator that employs directionalantennae for scanning the territory to be viewed, the output of saidantennae being detected and ampliiled and employed for trippingthermionic rectiiler means, the output oi which is used to control acathode ray tube, the deilecting plates of `which are synchronouslyenergized with -the operation of said antennae, whereby a spot is causedto appear on the screen oi.' said cathode ray tube in positioncorresponding to the position of an object, such as an airplane. in theterritory being viewed.

. Another object of the present invention lies in device of the abovecharacter wherein, in one form oi the invention, horiaontal and verticaldirectional antennae are rotated at a constant speed differential. thecommon means used for rotating said antennae being also used forcontrolling the application of voltages to the deilecting plates o! acathode ray tube so that. were this tube operating, the electron beamthereof would be made to traverse or scan the screen of the tube insynchronism with the scanning of the territory to be viewed by theantennae, the output oi said antennae being combined and then detectedand amplified for application to the grid of a grid controlled rectifierconnected for turning on the cathode ray beam when both antennae areaimed at the transmitter oi the object to be viewed, i. e., when spots.

Still another object ofthe present invention is to provide a noveldirection indicator of the above character wherein, in another form oithe l0 invention, horizontal and vertical fixed directional antennae areemployed, the outputs of which are commutated and applied in sequence todetector amplifier means, the output of which is used for feedingthermionic rectii'ler means ll used for controlling the operation of acathode raytube having potentials applied to its deilecting plates insynchronism with the commutation of said antennae, whereby a spotappears onthe screen of the tube in correspondence with the 20 positionof the oblect viewed.

Other objects and advantages will become apparent from thespeciiication, taken in connection with the accompanying drawings,wherein the invention is embodied in. concrete form.

1n the drawings. 1

Fig. l ls a fragmentary `view showing an aircraft equipped with one formoi the novel direction indicator device of this invention. f

Fig. 2 is a wiring diagram of this form of the 30 invention.

Fig. 3 is a view in front elevation, partly broken away, of the face ofthe cathode ray tube used.

Fig. 4 is a view in elevation and partly in section, of the singleantenna employed for scan- 35 ning both in azimuth and elevation.

Fig. 5 is a view, in elevation, of the system of this invention employedin a radio locator for use in gunilre control.

Similar characters of reference are used in 4g all oi the above ilguresto indicate corresponding parts.

Referringnow to Figs. l and 3, the reference numeral I designates anairplane equipped withan azimuth scanning directional antenna con- 4|sisting o! a reflector l of parabolic cross-section having an antennaconductor I positioned at its i'ocus, the reector 2 being arranged to berotated about a vertical axis. The craft i is also equipped with anelevation, scanning directional 50 antenna consisting of a rei'iector Ioi parabolic cross-section having an antenna conductor 5 positioned atitsiocus. the reilector l being adapted for rotation about a horizontalaxis.

Asespecially illustrated in Fig. 2, the reflector 5| driven by the shaftl,

` is connected by a lead 2l 2 is shown carried by a vertical -shaft lthat is driven through worm and wheel reduction gearing 1 from a motorl, while the reector l is shown driven directly from the motor i. Ashaft 9 is driven from shaft I and rotates `a resistor contact army Il,cooperating with a semicircular potentiometer resistor II, at the samespeed as reflector 2. Batteries I2 and I2' have unlike terminalsconnected together and to a center-tap oi.' resistor Il by leadl I2,while the remaining terminals of these batteries are connected by leadsIl and Il to the terminals of resistor Il. I ead Il is connected by leadI5 to one of the horizontal deflecting plates I land to one of thevertical deiiecting plates I1 ofthe cathode ray tube Il. The remaininghorizontal deiiecting plate is connected by lead I9 to the resistor armIII, while the remaining vertical deectlng plate to a resistor arm 2|driven trom the shaft I' of motor l at the same speed as that ofvertical scanning reflector l.

I'he anode 22 of tube Il is supplied from the positive side 2l of a D.C. source, while the negative side 2l of this source is connectedthrough lead 4I, resistor 42, leads Il grid 2l of tube Il, therebynormally'biasing this tube to ol! condition. The cathode Il is connectedthroughs portion of resistance 4I to the negative side 2l of the source.The negative lead 2l is also connected the contact arm 20 aigaging asemicircular conducting segment 2i for that half of each,revolution ofshaft I during which the resistor contact arm Il is out of engagementwith the resistor II. Segment is connected by lead 2l 'to the controlgrid 2l. The resistor arm 2| issimilartoarm Iland cooperateswith'asemicircular potentiometer resistor 21 having its mid-tap connected tolead I3 an`d its ends connected to leads I4 and Il.

The control grid 2l of cathode ray tube Il is also connected by leads 29and 2 toa semicircular conducting segment 3l arranged concentricallywith the resistor 21, which conducting seg'- ment is arranged to beengaged by a contact arm 3| that isy iixed on though insulated frommotor shaft I so as to rotate with this shaft, the arm 3| enggingsegment30 for that half of each revolution of'arm 2| during which this latterarm is out of engagement with resistor 21. The negative lead 2l is alsoconnected to arm II.

The horizontal scanning antenna I and the vertical scanning antenna lare connected' through shielded antenna leads Il and il to coils 3l andIt, respectively, which are arranged in inductive relation to theinputcoil l1 of a detector and audio ampliner Il. The rotating antennareflectors 2` and l have the eect of impressing amplitude modulations`upon vthe unmodulated carrier wave received from the transmitter of theobject which is being viewed or which isrreilected from such object.Preferably. the carrier wave is of ultra high frequency, not onlybecause the same can `be generated and received by simple means, butthese waves `easily penetrate f are not appreciably interfered with byuncontrollable natural phenomena such as radiation from the sun, and canbe detected directionally with-comparative ease. U. H. F. `waves ofapproximately 600 mc./sec. are entirely satisfactory. a

In use, as will further appear, it is necessary for the slower rotatingantenna reflector, illustrated asrenector 2 in the drawings, to rotatefast enough so as to prevent flicker on the screen as or the cathode mytube Il. In` practice; it has .hand end of and 2l to the control Y to acontact arm 2l, also- .measured from `starboard of the craft' uponwhichV the sameis y mounted. As this assises been found that to preventmeker, the reflector 2 should rotate at a speed of 750 R. P. M. or over,and as the ditlerential speed between renector 2 and reilector I willdetermine the number of scanning lines provided on the face Il of tubeIl,

. it is essential that the reflector I travel at a conthe reiiector R.P. M.. then the vertical scanning antenna I Should rotate at 375 R. P.S. or 22,500 R. P. M.

In scanning the face II of tube Il, it will be noted that when contactarm Il is at the left resistor II, this arm receives the mamum negativepotential provided by batteries I2 and I 2' and applies this potentialto the right hand horizontal deilecting plate of the tube I0.asshowninFig. 2, thereby causing the cathode ray beam (should the tubebe operating) to move to the left hand end of its travel on face orscreen ll of tube Il. The reiiector 2 is so arranged angularly withrespect to contact arm I 0 that when this contact arm is engaging theleft hand end oi' resistor Il, i. e., when arm I0 lpoints to the leftside o'f the sheet, then the reflector 2 will also point to the leftside of the sheet'i'or receiving rays from that, direction, and as thisreflector 2 sweeps forwardly. the arm Il sweeps downwardand when thereiiector 2 points directly ahead, as shown in Fig. 2, the arm Il pointsdirectly downwardly,v as shown in this figure, and when reflector 2turns so as to face the right hand side ofthe sheet,the arm I0 will alsopointin this direction, so that this arm Il is in contact with resistorII for that half of the revolution of reflector 2 while this reflectoris scanning 180 port forwardly through 180 to renector 2 moves throughthis scanning arc from left'to right, the moves from left to right,causing the cathode ray beam (if the same were on) to move transverselyacross the face I! of the tube Il. Actually, this beam is only on whenboth reflectors 2 and 4 are directed at the object being scanned, i. e.,when the outputs of the directional antennae l` and l are at theirmaximum, as will further appear. arm Il in the both horizontal to leadIl,A so

180 forward arm Il also position shown in Figs. l and 2,

that the imaginary cathode ray beam is at the center of the face 39.When arm Il reaches the right hand end of resistor II, the right handhorizontal plate Il is connected to lead Il', thereby causing theimaginary cathode ray beam to be positioned at the right hand end of itstravel.

While this cathode ray beam is traveling transdeiiecting plates Il areconnected.

It will be noted that with the"v vversely across screen 39, it is alsobeing made to scan this face vertically by the action of resistor 21 andcontact arm 2I. 'I'his will be apparent when it'is noted that arm 2|makes 30 revolutions to one revolution of arm Il, so that the cathoderay` beam -(imagining the same to be on) makes 30 vertical es acrossscreen I! while making one transverse passage thereacross,

producing the scanning effect as shown in Fig. 3 by the dotted lines 4l.'l Actually, these lines do not appear in the face of -the screen,because the tube isbiased to oil' position, as previously pointed o ut,by having its control grid connected to negative Y lead 2l.

tnegndortubeaatotnerebydetermmeetwm the magnitude of the output of thedetector-ampiiner necessary to eifect the discharge of tube 49. Tube Ilhas its plate-cathode circuit supplied preferably with high frequencyvoltage, i. e., voltage of preferably at least 1000 cycles. so that thistube shuts of! immediately the outputof the detector-amplifier hasfallen below'its maximum, i. e., below that obtaining when bothvantennae areaimedatthetransmitteroftheaircraftbelng viewed. The bias ontube I9 determined by po-k tentiometer il and grid resistor Il is suchthat tubeonlydischargesatthetimeofmaximum voltage output of thedetector-ampliiier.

The discharge of tube 49 produces a voltage drop across the resistor I!in the plate circuit of this tube. thereby raising the potential on the'grid 29 of cathode ray tube I9 and causing thel tube to operate -so thata spot appears on the screen 99 corresponding, in position to the objectbeing viewed. Thus, if the indicator apparatus of this invention ismounted on an airplane, it will scan through a forward hemisphere whoseaxis coincides with the line of flight and the screen I9 will giveditically and in miniature the bearings of the approaching aircraft inazimuth and elevation. It will be noted that when tube 48 passescurrent, the right hand end of resistor 42, connected by leads l49 and29 to the control grid of tube Il, becomes positive with respect to itsleft hand end that is connected by lead to the negative side 24 of thesource,'so that the control grid potential is raised, starting thecathode ray beam of tube I9, which beam is properly deflected by thepotentials on deecting plates Il and l] l to provide a spot Il at theproper location on screen 39. l

It will be noted that when contact arms i0 and 2l are 'out of engagementwith their respective resistors Il and 21, corresponding to movements oireflectors 2 and l through the rear halves of their revolutions, thecontact arms29 and Il are in engagement with their cooperating contact.

segments 20 and Il, thereby short circuiting the resistor 42 andpreventing the tube I9 from operating-while the antennae I and 9 arescanning the rear halfof theircircular arcs.

It `will be noted that any number of objects within the 180 solid anglescanned by the antennae will be indicated in their proper positions byspots on the screen I9. Displacement of a spot on this screen tothe leftor right, up or down, gives dltlcally and in miniature the position ofthe object, such as an aircraft, viewed relative to the nose of theobserving aircraft.

When the device is used on an aircraft for preventing collision withother aircraft, a circle 52 (see Fig. 3) is preferably provided at thecenter ofthe screen 39 to indicate that if a spot of light is withinthis circle, danger of collision is imminent. Horizontal and verticalguide lines 93 and 59 are also preferably provided on screen 39 toprovide reference lines and to divide the screen into quadrants.Collision is to be expected when the spot of light remains within thecircle and gets larger. or when the spot l0 remains still in anyposition on the screen while getting larger.

So long as the slower reector 2 rotates at '150 R. P. M. or higher,persistence of vision will prevent iiicker on the screen I9, or by usingsuitable fluorescent material having a time delay in the decay of itsluminosity on screen 99. lower rates of rotation are feasible withouticker. Also, the speed of the directional antennae may be cut in half byusing loops or bi-directional antennae instead of parabolic reflectors.

When using the device of the present invention for gunfire control, aswhen locating aircraft `from the ground, a suitable U. H. F. transmitteris provided on the groundv and the reflected rays from the viewed objectemployed for operating the indicator of this invention.

Obviously, if it is desired to scan more or less than 180 in the form oithe invention shown in Figs. 1 and 2, the angular extent of thepotentiometers VI I and 21 will be varied accordingly.

Also, a single antenna mounted universally may be used for scanning thedesired iield of view inl stead of the two antennae shown in theforms ofthe invention heretofore described. Thus, in Fig. 4, an ultra highfrequency antenna 91 is mounted within a parabolic reflector 99 that iscarried .by a horizontal shaft 99 driven from motor 9 through gearing 90and sprocket chain 9|. Thus, the motor 9 is adapted to rotate thereflector 99 about a horizontal axis so as to scan in elevation at thesame rate of sped las that of the reector l of Figs. 1 and 2. Similarly,the reiiector 99 is rotated about a vertical axis by means of motor 9operating, through reduction gearing 92, to turn gear 92 and attachedyoke 92 carrying the ends of shaft 09. Thus, the yoke 93 is revolved ata definite speed ratio with respect to the speed of reflector 99 aboutits horizontal axis, the speed ratio being, for example, 30:1, as in theprevious forms of the invention, the turning of the yoke 99 about avertical axis providing the azimuth scanning of the antenna. 'I'heoutput of antenna 91 is connected through the slip ring and brushcombination 94 to the coil 95, inductively related to coil 31 connectedto the detector and audio amplifier 99, as in Figs. 1 and 2 of thedrawings. The potentiometers (not shown) `will be operated on the motorl, similarly to those. i. e., Ii and 21, shown in Figs. 1 and 2.

When using the device of the present invention for ,gunfire control, itis preferable that the v U. H. F. transmitter move with the receivingantenna so that the maximum reflected signal shall be received. Thus, inFigs. l and 2, the U. H. F. transmitter 90 supplies an antenna 91 whoserotating reector 90 is driven at the same speed as the reflector ,2 andis arranged in the same phase position as the reflector 2 at all times.Similarly, the vertically scanning reflector (not shown) ot thetransmitter 99 would be operated from shaft 9', so that thesetransmitting antennae act to direct the transmitted waves in directionscorresponding to the directions of reception of the receiving antennae.

In Fig. 5, a typical radio locator arrangement for gunfire controlapparatus is shown. Parts of this equipment which are similar to thosein Figs. 1 and 2 are correspondingly numbered. In this gure, thevertical scanning transmitting antenna 99, having the rotating reflector|00, is also shown. It will be noted that all of the antenna reflectorsare driven from the motor 9, the horizontal reectors l and |00 rotating,i for example, times as fast as the vertical 7o antennae. This equipmentis mounted on a platform |0I that has trunnions |01' journaled inbearings provided in a yoke |02. A handwheel |09 is connected throughgearing i0l' for turn- I ing the platform IOI, and hence thetransmitting 75 nsv and receiving equipment. in'elevation.Similarly,theyoke Illistdnptcdtobcturnedinasimuth by means of thehandwheel I, acting through the gearing shown.- The cathode ray tubes I!are provided at eachendof'theyoke Il! so as to be-convenientlyvisible tothe personsv operating handwheels Il! and Ill. The U. H. F. transmitterequipment Il, the detector and amplifier 3l, and associated apparatusincluding the cathode Vray tube control, are all mounted on the platformIII.' Preferably, s. suitable shield Ill is located between thetransmitting and receiving equipment to prevent interference.

In order to'take oi! the elevation and azimuth movements of thetransmitting and receiving equipment for use in operating guns orgunfire control directors, transmitting Selsyns Ill and Ill areemployed. The Selm i is operated from handwheel |03 for setting in theelevation indication for the gunilre control director, whereas theSelsyn Ill is operated from the handwheel Ill for setting in the azimuthindication for the gunfire control director.

In use, as soon as an object, such as an plane, appears on the screen 3lof the cath ,l ray tube Il, the `operators of handwheels/ill and i turnthese wheels soas to brir the cathode ray spot on the screen 3l to thecenter of the screen, thereby indicating that the object is in thecenter of view of the cathode ray screen,

the antenna equipments at that time pointing directly toward the objectwhen at the center of their scanning ranges. 'Ihe necessary movements ofhandwheels I and I for accomplishing this resultprovide the ninformation for the guniire control directors to set the guns vupon thetarget.

As many changes could be made in the above construction and manyapparently widely diii'erent embodiments of this invention could be madewithout departing from the scope thereof, it is Y intended` that allmatter contained in' the above vim description or shown in theaccompanying drawings shall be interpreted as illustrative and not in alimiting sense. l

What is claimed is: f

1. In a tridimensional radio direction indicator, azimuth and elevationdifferentially rotating directional antennae, a cathode ray tubenormally biased to inoperative condition, potential varying meansrotatable in synchronism with said antennae for varying potentials onthe deflecting plates' of said tube, whereby, were said tube inoperation, the beam -thereof would scan the screen of said tube insynchronism with the scanning operation of said antennae, and thermionictube means supplied from said antennae for reducing the bias on saidcathode ray tube and efl'ecting the operation of said cathode ray tube*when both of said antennae are receiving the `maximum signal from theobject viewed, whereby the screen of said tube is caused to indicate thebearings of saidyobject in azimuth and elevation. f

2. In a tridimensional radio direction indicatorl azimuth and elevationdiiferentially rotating directional antennae, a cathode ray tubenormally biased to inoperative condition, potential varying meansrotatable in synchronism with said antennae for varying potentials onthe deilecting plates oisaid tube, whereby, were said tube in operation,the beam thereof would scan the screen of said tube in synchronism withthe scanning operation of *said antennae, thermionic tube means suppliedfrom said antennae for reducing the bias on'said cathode'ray tube andeii'ecting the operation of said cathode ray tube when both oi said anare-receiving the' maximum signal from the object viewed, whereby thescreen of said tube is caused to indicate the bearings of said object inazimuth and elevation, and means associated with said potential varyingmeans for limiting the scanning operation of said cathode ray tube to a180 solid angle.

3. In a tridimensional radio direction indicator, azimuth and elevationdifferentially rotating directional antennae, a cathode ray tubenormally biased to inoperative condition, potential varying meansrotatable in synchro with said antenna for varying Potentials on thedeiiecting plates ofl said tube, whereby, were said tube in operation,the beam thereof would scan the screen of said tube in synchronism withthey scanning operation oi said antennae, a detectorampliiier suppliedfrom said antennae. and a grid controlled rectifier in the outputcircuit of ,said detector-amplifier tter, said rectifier being connectedto start said cathode ray tube when both of said antennae are directedtoward the object scanned and are receiving'maximum signal therefrom,whereby a spot appears on the screen of said tube i'n synchronousposition with that of the object scanned. V

4. 2in` an apparatus i'or` locating objects, Acomprising directionaltransmitting antenna means and receiving antenna means. means forrotating said transmitting and receiving antenna means in. synchronismfor scanning a desired range, detector and amplier means fed from saidreceiving antenna means, indicator means connected with said detecto-ampline'r means and ladapted toindicate the scanned by said antennameans, and means for moving each said antenna means in accordance withthe indications of said indicator so that each said antenna means isdirected toward the object when at the center of its scanning range. 5.Inv an apparatus for locating objects.v comprising directionaltransmitting antenna means and receiving antenna means, means forrotating said transmitting and receiving antenna mens to be controlledby the location `of an object I in synchronism for scanning a desiredrange, de-

with said detector-amplifier means and adapted to indicate the locationof an object scanned by said antenna means, manually operable' means formoving said antenna means in accordance with the indications of saidindicator so that Said antenna means are directed toward the object whenat the center of their scanning range, and means operating in responseto movement of said manually operable means for controlling a gunrecontrol director.

6. A` non-optical anti-aircraft fire control system,vincluding radiodirectional transmitting and receiving antenna means rotatable about ahorizontai axis, a second radio directional transmit- I ting andreceiving antenna means rotatable about a vertical axis, a main frameadjustable in azimuth and elevation upon which both of said antennameans are rotatably mounted. and means for orienting and elevating saidtrame from the signals received by said antenna means, to give thetarget bearings and angular elevation.

7. ,Inr apparatus for locating objects, continuously rotating antennameans for scanning a viield t of view both in azimuth and elevation. acathode ray tube normally biasedrto inoperative condition, potentialvarying means rotatable in synchronism with said antenna means forvarying potentials n the defiecting plates of said tube, whereby, weresaid tube in operation, the beam thereof would scan the screen -of saidtube in synchronism with the scanning operation of said antenna means,and thermionic tube means having a grid, filament and plate with itsgrid circuitl controlled from said antenna means and having a highfrequency alternating current dlrectly applied to the plate of saidtube, said tube means being connected to reduce the bias on said cathoderay tube and momentarily etl'ect operation of said cathode ray tube inresponse to the reception oi a maximum signal obtaining .upon thedirecting oi' the antenna means directly at the object scanned, wherebythe screen of said tube is caused to indicate by a spot thereon the`bearings of said object` in azimuth and elevation.

8. A tridimensional radio direction indicator as dened in claim 7,wherein orienting means is provided for moving said antenna meansangularly in azimuth and elevation so that the spot on the screen ofsaidtube remains on the center of said screen while tracking the object,and means for picking oil the azimuthal and elevational movements oi'said orienting means.

9. In a tridimensional radio direction indicator, azimuth scanningrotating antenna means. elevation scanning rotating antenna means, saidazimuth and elevation antenna means having a definite speed ratiotherebetween, a cathode ray tube having a control grid and deiiectingplates, potentiometer means operated in accordance with the speeds ofrotation of said azimuth and elevation antenna means and connected tothe deflecting plates of said cathode ray tube for applying beamdeecting potentials thereto in synchronism with the scanning operationsof said antenna means, a detector-amplifier fed from said azimuth andelevation antenna means, a grid controlled rectifier having its inputcircuit fed from said detector-amplier and having a resistor in itsoutput circuit connected in the control grid circuit of said cathode raytube, means for normally biasing said grid controlled rectiiier ofi',and means for supplying the plate of said rectier directly with highfrequency alternating` current io'r controlling the operation of saidcathode ray tube, whereby the latter only passes current for the momentthat both antenna means are simultaneously directed at an object tothereby indicate synchronously and in miniature objects viewed by saidazimuth and elevation antenna means.

JOSEPH LYMAN.

